fzero_vec, integral_vec and spline are now local functions in Curve. Renamed arcLengthStretch to arcLengthParametrization. Removed plot_derivative. Added some comments and extra lines + removed unneccesary lines. arcLength is now a method and not static. Constructor does not accept difference operator anymore.

% Creates a matrix of size n,m with the values of val on the diagonals diag.
function A = stripeMatrix(val,diags,n,m)
    default_arg('m',n);

    D = ones(n,1)*val;
    A = spdiags(D,diags,n,m);
end